Reference Interval

Specimen Requirements

Specimen

Container

Two full lavender-top (EDTA) tubes and one red-top tube or gel-barrier tube

Patient Preparation

Verify that the patient has not had vitamins containing folic acid during the previous three to five days; if so, consult the physician.

Collection

Transfer 7 mL from one whole blood tube into a plastic transport tube and freeze. Refrigerate second whole blood tube. If a red-top tube is used, transfer separated serum to a plastic transport tube. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.

Storage Instructions

Freeze whole blood transport tube and refrigerate all other specimens.

Causes for Rejection

Clinical Information

Special Instructions

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.